Specialized Allez to Bullhorn and 1x8 Conversion
 

I ride a 2013 Specialized Allez Comp and would like to swap the drop bars for bullhorns and possibly convert to 1x8. I'm thinking the cleanest and easiest way to do it would be with a mountain bike style brake / shifter combination for the rear. The front would just be a basic brake lever since the front derailleur would be removed.

Have any of you guys done this? Is this possible, or is it much or complicated than I'm thinking?

My bike's specs as it sits now (stock):

HEADSET
1-1/8" sealed Cr-Mo cartridge bearings integrated w/ headset, 20mm alloy cone spacer, w/ 20mm of spacers
STEM
Cast alloy, 4-bolt, 31.8mm
HANDLEBARS
Specialized Comp, 6061 alloy, shallow bend
FRONT BRAKE
Tektro dual-pivot
REAR BRAKE
Tektro dual-pivot
BRAKE LEVERS
FRONT DERAILLEUR
Shimano 2300
REAR DERAILLEUR
Shimano 2300
SHIFT LEVERS
Shimano 2300 STI
CASSETTE
Shimano HG-50, 8-speed, 12-25
CHAIN
KMC Z51
CRANKSET
Shimano 2300 compact
CHAINRINGS
50/34
BOTTOM BRACKET
Sealed cartridge, square taper, 68mm

If you really want to do this, and I consider hipster style conversions a bad idea, the easiest thing to do is to get some cantilever type brake levers and a bar end shifter or thumb shifter, although an MTB trigger shifter would work with a road rear derailleur. You'll also want to sort out some chain retention at the front like a dog tooth and a guard ring. Do not try to use MTB brake levers because the cable pull ratio is wrong and your brakes will have no stopping power.
I've never done this to a modern bike but I did convert an old Peugeot to North Road style bars and thumb shifters a few years ago using Velo-Orange stuff.

The trigger shifters ONLY come in MTB standard clamp sizes :-/ Which is a big issue considering bullhorns and drop bars just don't come in those sizes.

Does anyone know where I can get an 8 speed trigger shifter that'll clamp onto a road handlebar diameter?

Go in for thumb shifters instead ..

Interrupter levers work well on bullhorn, and will play nice with a bar end shifter. Here's a video showing how I did it. It continues to work very well.

to make it a one-by-anything all you have to do is remove the front derailleur. you can remove extra chainrings and extra chain links if you want. that's the first half.

as for handlebars... many bullhorns have the same stem and brake clamping diameters as road bars. so you can swap them out without any trouble. you may not be satisfied with STI levers on bull horns... soooo

you can solve any braking issues with cyclecross interrupter levers. and NO they do not have to interrupt anything. they can stand alone, despite what those who have never tried it will say. and as for shifting duties...

i looked and didn't find any shimano compatible 8-speed trigger type shifters with a road bar clamp (not including twistshift or barend). it may require some REAL digging or improvisation. FYI, i did manage to get an MTB trigger lever designed with a clamp for an MTB bar to work on a road bar, but i had to customize it myself. a little, okay a lot, of work with a half round file on the clamp finally produced and acceptable result. YMMV.

BTW, i mounted my interrupters a couple of inches outboard of the stem clamp. pretty much where they are on cyclocross bikes. it's not necessarily a recommendation. and in the previous video the brake cables are reversed from the way i use my interrupters.

Dan, that all came out very nice.

I have to admit that my first thought at reading that you used interrupter levers was the common issue with the cables not having a proper seating so they avoid kinking and fraying. But your choice of levers with the barrel adjusters to set the end thimble out and away where it's protected is brilliant. I don't know if it was good luck or good planning but it avoids a possible issue of using interrupter levers neatly.

To those that champion the interrupter lever for all solutions. There was a thread a few years back about someone using interrupter levers that put a strong bend on the cable where it fit in the thimble end. The result was that the cables soon frayed and broke. It's important that the cable where it comes out of the cast or swaged on end thimble is supported against bending while in use.

IME, when interrupter levers are used as interrupters between brifters and caliper, as on most cross bikes, or used stand-alone the cable doesn't move, the housing does with respect to the handlebars. as used in the above video i can see how the cable might become prematurely frayed. good observation.

The way Dan used them it isn't an issue. The thimble sits out in the barrel adjuster so the cable is bending a little away from the transition to the thimble.

It's when the thimble sits hard in the other side and the cable gets flexed at the transition that it's bad.

Good reason not to wrap the bar tape too close, if I'm understanding you correctly? (When used as actual interrupter levers?)

The issue isn't when they are used inline like they were intended for doing. It's when we use them as final levers and have to terminate the thimble somewhere that isn't normally used for such things. Like you've done by using interrupter levers as end levers instead of inline.

The original issue arose, IIRC, when the other guy used them as primary levers on mountain bike style bars. He wanted nice tidy and small two finger levers. So he used them the right way around instead of backwards like you're doing. But he then set himself up to run into problems when he simply ran the road style end thimbles into the movable lever portion.

On normal levers the thimble sits into a pivoting block so it can turn. So it keeps the thimble in line with the cable pull. But interrupter levers don't have that pivot. So every time he pulled on the levers the cable was being pulled into a sharp kink right at the thimble. And after a couple of months he broke one cable and noticed fraying on the other.

Part of his issue was also that he kept his levers set up fairly loose. So the cable had to move a lot. But in the end it was really the lack of a pivot or any way of moving the thimble out to where it can be stable.

Your levers don't have any pivot. But you've put the thimbles into the adjuster barrels. So the cable right where it comes out of the thimble is not going to see any bending. And that's the good thing. So you should be OK. But I'd keep a close eye on the cables where they flex in the lever for some time just to be sure.

This is incorrect for bullhorns. They are available if you bother to look around the internet.

Or just get a flat bar and some bar ends. 90%of the look and functionality of a bullhorn at 10% of the effort. Wrap with bar tape and you need to be really close to see the difference.

No.

OK, gotcha.

"A 2013 Allez comp with a compact double crankset and an 8-speed cassette?"

If that's what you think would make you happy - just do it. You're the only person in the whole world that bike has to please.

The cheap way to do the handlebar is to flip it over and hacksaw off the ends at the curve.
I'd argue that the best and coolest way to do the shifter would be a bar end which will work with a flopped and chopped handlebar. Don't worry about speeds, just use friction mode.
Chain line can be a sticky. Ideally you'd want your chainring to exactly bi-sect your cassette. If it was my bike I'd just try whichever chainring you plan to use where it is now and not bother with a different bottom bracket spindle unless you find the chain likes to unship itself. It might not. You'll need a set of shorter chainring bolts.

That leaves brake levers. Brakes are over rated. All they do is slow you down but, when you need them, you need them. I wouldn't do this on a customer bike but I'd use interrupter levers on a personal bike. Just inspect the cable every now and then.

Better is reverse levers made for the purpose .. the cable end is let float so the pull is straight , not flexed..

As noted in another thread PaulComp makes one usable in V or road type brakes & cantilevers .

nice USA made CNC CAM lifetime stuff.. .

Actually, I've been looking for days and haven't located any. The Shimano 8 speed trigger shifters that I've been wanting to use don't list a clamp size, so I'm assuming they're 22.2mm, since that's what modern mountain bike grip width is. If you know of any website that sells bullhorns / pursuit bars with a 22.2mm grip diameter, please give me a heads up! I don't care about the clamp diameter because I plan on swapping my current 105mm stem to a 60 or 70mm anyway.


And speaking of stems... Does anyone know what angle I would need to get a stem to make it perfectly level? Specialized doesn't list the angle of the stock one, so I'm not sure what my starting point is.

Specialized Bicycle Components

Fabrik Bullhorn Handlebar - Black

Or here:
New on one bars preview | Products | News | On-One Bikes
Scroll down a bit.
Or try to find a pair of Old school brahma bars. Or flat bar + bar ends.

The Fabrik bars are perfect, but ordering from Europe seems a little much... Is there anything in the states? The On-One bars are nice too, but they don't offer the 22.2 anymore :-(

Starting point doesn't matter. Simple geometry: 90 deg minus head tube angle. Head tube angle varies with frame size, so you'll need to look yours up.

I just typed "22.2 bullhorn" into Google. Those two were on the first page. You should be able to find some closer to home. Or do flat bar and bar ends. You'll be out riding in no time. Sure, a bullhorn would be more elegant, but functionally they're indistinguishable.

seventeen degrees. don't use your real headtube angle, even if you know it, they only make stems in a limited number of angles.

Is a -17 degree stem the same as a 73 degree stem?